iTunes notification

So just opend WOTB like I usually do only now I get a prompt from my iPhone saying itunes store is unable process purcases at this time try again later. With of course an ok button. No other app or game or even iTunes itself is doing this. What gives?

No, it is not. This problem will solve itself with time. Many players have several dozens of vehicles in their Garages, so they don’t have enough Spare Parts for the entire vehicle fleet. But you will gradually collect enough Spare Parts to unlock new slots for purchased tanks in time.